Zi 字媒體
2017-07-25T20:27:27+00:00
C# 彩色圖片/照片 轉灰階&二值化(單色BMP)
資料來源:https://blog.holey.cc/2018/04/18/csharp-three-way-covert-bmp-rgb-to-gray/
http://hk.uwenku.com/question/p-qnyytjbn-bco.html
GITHUB: https://github.com/jash-git/CS_RGBtoGray_1Bit
CODE:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace CS_RGBtoGray
{
//https://blog.holey.cc/2018/04/18/csharp-three-way-covert-bmp-rgb-to-gray/
//http://hk.uwenku.com/question/p-qnyytjbn-bco.html
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
public Bitmap RGBtoGray01(Bitmap bmpSrc)
{
Bitmap bitmap = new Bitmap(bmpSrc);
for (int y = 0; y < bitmap.Height; y++)
{
for (int x = 0; x < bitmap.Width; x++)
{
int gray = (
bitmap.GetPixel(x, y).R +
bitmap.GetPixel(x, y).G +
bitmap.GetPixel(x, y).B) / 3;
Color color = Color.FromArgb(gray, gray, gray);
bitmap.SetPixel(x, y, color);
}
}
return bitmap;
}
public Bitmap RGBtoGray02(Bitmap bmpSrc)
{
Bitmap bitmap = new Bitmap(bmpSrc);
BitmapData bmpData = bitmap.LockBits(
new Rectangle(0, 0, bitmap.Width, bitmap.Height),
ImageLockMode.ReadWrite,
bitmap.PixelFormat);
unsafe
{
int stride = bmpData.Stride;
int offset = stride - bitmap.Width * 3;
IntPtr intPtr = bmpData.Scan0;
byte* p = (byte*)(void*)intPtr;
for (int y = 0; y < bitmap.Height; y++)
{
for (int x = 0; x < bitmap.Width; x++)
{
byte gray = (byte)((
p[y * (bitmap.Width * 3 + offset) + (x * 3) + 0] +
p[y * (bitmap.Width * 3 + offset) + (x * 3) + 1] +
p[y * (bitmap.Width * 3 + offset) + (x * 3) + 2]) / 3);
for (int i = 0; i < 3; i++)
{
p[y * (bitmap.Width * 3 + offset) + (x * 3) + i] = gray;
}
}
}
}
bitmap.UnlockBits(bmpData);
return bitmap;
}
public Bitmap RGBtoGray03(Bitmap bmpSrc)
{
ColorMatrix cm = new ColorMatrix(new float[][]
{
new float[] { 0.30f, 0.30f, 0.30f, 0.00f, 0.00f } ,
new float[] { 0.59f, 0.59f, 0.59f, 0.00f, 0.00f } ,
new float[] { 0.11f, 0.11f, 0.11f, 0.00f, 0.00f } ,
new float[] { 0.00f, 0.00f, 0.00f, 1.00f, 0.00f } ,
new float[] { 0.00f, 0.00f, 0.00f, 0.00f, 1.00f }
});
ImageAttributes ia = new ImageAttributes();
ia.SetColorMatrix(cm);
Bitmap bitmap = new Bitmap(bmpSrc.Width, bmpSrc.Height, bmpSrc.PixelFormat);
Graphics g = Graphics.FromImage(bitmap);
Rectangle rect = new Rectangle(0, 0, bitmap.Width, bitmap.Height);
g.DrawImage(bmpSrc, rect, 0, 0, bitmap.Width, bitmap.Height, GraphicsUnit.Pixel, ia);
return bitmap;
}
public Bitmap ConvertTo1Bit(Bitmap input)
{
var masks = new byte[] { 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01 };
var output = new Bitmap(input.Width, input.Height, PixelFormat.Format1bppIndexed);
var data = new sbyte[input.Width, input.Height];
var inputData = input.LockBits(new Rectangle(0, 0, input.Width, input.Height), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
try
{
var scanLine = inputData.Scan0;
var line = new byte[inputData.Stride];
for (var y = 0; y < inputData.Height; y++, scanLine += inputData.Stride)
{
Marshal.Copy(scanLine, line, 0, line.Length);
for (var x = 0; x < input.Width; x++)
{
data[x, y] = (sbyte)(64 * (GetGreyLevel(line[x * 3 + 2], line[x * 3 + 1], line[x * 3 + 0]) - 0.5));
}
}
}
finally
{
input.UnlockBits(inputData);
}
var outputData = output.LockBits(new Rectangle(0, 0, output.Width, output.Height), ImageLockMode.WriteOnly, PixelFormat.Format1bppIndexed);
try
{
var scanLine = outputData.Scan0;
for (var y = 0; y < outputData.Height; y++, scanLine += outputData.Stride)
{
var line = new byte[outputData.Stride];
for (var x = 0; x < input.Width; x++)
{
var j = data[x, y] > 0;
if (j) line[x / 8] |= masks[x % 8];
var error = (sbyte)(data[x, y] - (j ? 32 : -32));
if (x < input.Width - 1) data[x + 1, y] += (sbyte)(7 * error / 16);
if (y < input.Height - 1)
{
if (x > 0) data[x - 1, y + 1] += (sbyte)(3 * error / 16);
data[x, y + 1] += (sbyte)(5 * error / 16);
if (x < input.Width - 1) data[x + 1, y + 1] += (sbyte)(1 * error / 16);
}
}
Marshal.Copy(line, 0, scanLine, outputData.Stride);
}
}
finally
{
output.UnlockBits(outputData);
}
return output;
}
public double GetGreyLevel(byte r, byte g, byte b)
{
return (r * 0.299 + g * 0.587 + b * 0.114) / 255;
}
public Bitmap BitmapTo1Bpp(Bitmap img)
{
int w = img.Width;
int h = img.Height;
Bitmap bmp = new Bitmap(w, h, PixelFormat.Format1bppIndexed);
BitmapData data = bmp.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadWrite, PixelFormat.Format1bppIndexed);
byte[] scan = new byte[(w + 7) / 8];
for (int y = 0; y < h; y++)
{
for (int x = 0; x < w; x++)
{
if (x % 8 == 0) scan[x / 8] = 0;
Color c = img.GetPixel(x, y);
if (c.GetBrightness() >= 0.7) scan[x / 8] |= (byte)(0x80 >> (x % 8));
}
Marshal.Copy(scan, 0, (IntPtr)((long)data.Scan0 + data.Stride * y), scan.Length);
}
bmp.UnlockBits(data);
return bmp;
}
private void Form1_Load(object sender, EventArgs e)
{
Bitmap RGBtoGray = RGBtoGray03(new Bitmap("20210610094646.jpg"));
pictureBox1.Image = RGBtoGray;
pictureBox2.Image = BitmapTo1Bpp(new Bitmap("20210610094646.jpg"));
}
}
}
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